You can select the registered paper size from [Paper Size] in the [Print] or [Page Setup] dialog box.

NOTE

You can also set custom paper sizes from the dialog box displayed when you select [Page Setup] from the [File] menu of an application.

If the custom paper size you have set is not displayed in [Print] dialog box > [Paper Handling] preference pane > [Destination Paper Size], you cannot print using that paper size. You need to change the paper size.